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SBIR/STTR

Scandate Cathode for High Power Long Life Electric Propulsion, Phase I

Project Introduction

Scandate cathodes are proposed as a way to boost performance and life for electric space propulsion systems. This company has recently demonstrated breakthrough performance on these cathodes in other formats. We have demonstrated emission of 5 Amps/cm2 at 850 degrees CB, which is 200 degrees C below that of conventional cathodes. At this temperature they should live at least 100,000 hours. This makes scandate cathodes a candidate for use in deep space missions. In Phase I we propose construction and testing of several hollow scandate cathodes. We propose to do both vacuum and ion environment characterization on them. In Phase II we will begin active collaboration with NASA to test these cathodes in complete ion thrusters.
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Anticipated Benefits

NASA needs the cathode in ion thrusters, amplifiers for RF space communications, and terahertz sources and amplifiers. These tubes need very small cathodes with very high emission levels. The most pressing need is for space communications, primarily high-speed transmissions of video images from outer space. The frequencies most likely to use this cathode are 32 GHz and higher. This cathode must be miniaturized, an e beam specialty. But a larger cathode with low beam convergence in tubes below 32 GHz is also an option. In space applications, long life has been the overruling priority and cathode loading was secondary. But given the upsurge in high data rate applications, cathode loading is going up. e beam has worked with NASA Glenn and JPL to develop cathodes for these applications. Another NASA application is atmospheric research to excite molecular resonances in the 600 GHz to 1200 GHz region. JPL has been looking for sources and amplifiers such as reflex klystrons, BWOs (backward wave oscillators) or traveling wave tubes. The third NASA requirement is for ion thrusters. e beam received a contract from NASA Glenn to produce the RF source for the ion engine for the Jupiter Icy Moons Orbiter in 2004. Two approaches were taken: 1) use an RF source to excite the ions inside the ion chamber; 2) directly excite the ions with electrons produced by a hollow cathode. Both approaches require long life, and high cathode loading, such as proposed here.
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